United States Department of Agriculture

Date

Animal and Plant Health Inspection Service

Emerging Risk Notice

August 2020

Infectious hypodermal and 

hematopoietic necrosis virus 

(IHHNV)

Key Points

 In 2019, shrimp farms in Texas, Florida and 

New Mexico were quarantined with all affected 

tanks depopulated after the detection of 

IHHNV in shrimp. A research facility in 

California was also quarantined and 

depopulated after receiving shrimp from a 

previously infected farm.1

 IHHNV is a DNA virus of the family 

Parvoviridae which affects farmed and wild 

penaeid shrimp (of the Penaeidae family).2It 

has been reported in many regions of the 

world including Africa, Asia, Australia, Europe, 

and the Americas.1 

 IHHNV is reportable to the OIE (World 

Organisation for Animal Health). It is not 

known to pose a human health risk.

Concerns for U.S. Animal Health

 IHHNV is an emerging global disease first 

described in association with outbreaks of 

penaeid shrimp mortality in 1981 in Hawaiian 

shrimp culture facilities.3

 The U.S. is the only country in the Americas 

since 2006 considered by the OIE to have 

IHHNV-free zones.1

 The mortality rate associated with IHHNV 

varies, but may be as high as 80-90%.3 Low 

mortality with high morbidity entailing 

deformities and growth suppression, resulting 

in high commercial losses, has also been 

reported.4

 Commercial U.S. shrimp production in 2017 

was valued at $531 million.5

Epidemiology

 USDA-APHIS-VS is working to complete 

epidemiologic investigations.

 IHHNV has been identified globally in farmed 

and wild shrimp; mortality and morbidity varies 

depending on species.6

 Species which meet the OIE criteria for listing 

as susceptible to IHHNV include: yellowleg

shrimp (Penaeus californiensis), giant tiger 

prawn (P. monodon), northern white shrimp 

(P. setiferus), blue shrimp (P. stylirostris), and 

white leg shrimp (P. vannamei). Research 

suggests other potential host species may 

exist, but these have not yet met the OIE 

criteria for listing as susceptible to IHHNV.6

 Signs of acute IHHNV infection are most 

prominent in juveniles of P. stylirostris and 

include lethargic surface swimming, 

motionlessness or sinking shrimp, muscle 

opacity, and high mortality rates.7

 Chronic IHHNV infection causes runt deformity 

syndrome (RDS) in some species, most 

notably in P. vannamei, selected lines of P. 

stylirostris, and some populations of P. 

monodon. Clinical signs include cuticle 

deformities, deformed rostra, and variable and 

reduced growth rates.8

 Resistance may vary between penaeid 

species and also within different genetic lines 

of pinaeid species. P. vannamei is the 

principal global farmed shrimp species, largely 

due to its relative resistance to IHHNV 

infection.9

 IHHNV is transmitted horizontally and 

vertically through cannibalization, 

contaminated water, and infected eggs.3,10
United States Department of Agriculture

Date

Animal and Plant Health Inspection Service

Diagnostic Testing

 IHHNV primarily targets connective tissue cells, 

gills, haematopoietic nodules and haemocytes, 

ventral nerve cord and ganglia, antennal gland 

tubule epithelial cells, and lymphoid organ 

parenchymal cells. Any of the tissues listed 

above, pleopods, hemolymph, or whole shrimp 

or prawns may be used for testing.6

 Diagnostic testing methods include polymerase 

chain reaction (PCR), dot-blot hybridization, insitu hybridization, histopathology, and genetic 

sequencing.6

 Histopathological lesions include Cowdry type 

A intranuclear inclusions in gills, nerve cord, 

gastric mucosa, antennal gland, cuticular 

hypodermis, and hematopoietic and connective 

tissue.3

 Certain cuticular deformities are 

pathognomonic for infection with IHHNV, 

specifically, a deformed rostrum bent to the left 

or right which may be presented by P. 

vannamei and P. stylirostris with RDS.6

Treatment

 No treatments or vaccines are currently 

available for IHHNV.6

Prevention 

 Appropriate aquaculture biosecurity practices 

and husbandry are recommended to prevent 

disease introduction and spread. 

 Proper biosecurity practices include:

o Purchasing live shrimp and germplasm from

sources known to be free of IHHNV.

o Quarantining and monitoring all new shrimp 

stocks upon arrival to a farm, disinfecting and 

properly disposing of water used to transport live 

shrimp, noting increased mortality rates and 

using appropriate diagnostic testing.

o Pretreating all water sources and minimizing or 

eliminating water exchange between 

populations.9

o Routinely sanitizing equipment with appropriate 

disinfectants.11

Sources

1. OIE World Animal Health Information System Report 

Archive IHHNV. Available at: 

https://www.oie.int/wahis_2/public/wahid.php/Diseaseinfor

mation/reportarchive. Accessed January 2020.

2. Classification and nomenclature of viruses. Fourth report 

of the International Committee on Taxonomy of Viruses. 

Intervirology 1982;17:1-199.

3. Lightner DV, Redman RM, Bell TA. Infectious 

hypodermal and hematopoietic necrosis, a newly 

recognized virus disease of penaeid shrimp. Journal of 

invertebrate pathology 1983;42:62-70.

4. Rai P, Safeena MP, Krabsetsve K, et al. Genomics, 

Molecular Epidemiology and Diagnostics of Infectious 

hypodermal and hematopoietic necrosis virus. Indian J 

Virol 2012;23:203-214.

5. American seafood industry steadily increases its 

footprint. https://www.noaa.gov/media-release/americanseafood-industry-steadily-increases-its-footprint. Accessed 

September 2019.

6. Manual of Diagnostic Tests for Aquatic Animals (2019). 

Online access: OIE World Organisation for Animal Health.

7. Hsieh CY, Chuang PC, Chen LC, et al. Infectious 

hypodermal and haematopoietic necrosis virus (IHHNV) 

infections in giant freshwater prawn, Macrobrachium 

rosenbergii. Aquaculture 2006;258:73-79.

8. Kalagayan H, Godin D, Kanna R, et al. IHHN Virus as an 

Etiological Factor in Runt-Deformity Syndrome (RDS) of 

Juvenile Penaeus vannamei Cultured in Hawaii. Journal of 

the World Aquaculture Society 1991;22:235-243.

9. Lightner DV. Biosecurity in Shrimp Farming: Pathogen 

Exclusion through Use of SPF Stock and Routine 

Surveillance. Journal of the World Aquaculture Society

2005;36:229-248.

10. Motte E, Yugcha E, Luzardo J, et al. Prevention of 

IHHNV vertical transmission in the white shrimp 

Litopenaeus vannamei. Aquaculture 2003;219:57-70.

11. Biosecurity: Protecting Farmed Fish. 

https://www.inspection.gc.ca/animal-health/aquaticanimals/biosecurity/eng/1320594187303/1320594268146.

Accessed September 2019.

For more information contact: 

Dana Cole, DVM, PhD 

Risk Identification & Risk Assessment Director

Dana.J.Cole@usda.gov

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